The present invention relates to robots and more particularly to robot controls capable of providing curved path control.
In the prior art, robot motion over a curved path has typically been controlled by employing point-to-point programming to approximate the curve with a series of straight line segments and thereafter employing continuous path control for smoothing between path segments. As considered more fully in U.S. Ser. No. 932,985, continuous path control involves executing a smoothing transition between path segments having different slew velocities.
To follow a curved path closely with continuous path control, numerous points to be defined along the path, i.e., extensive programming labor is required. Further, by defining numerous points for the path, the robot tool tip typically cannot reach full speed because of the effects of smoothing. Finally, different robot speeds will result in different tool tip paths since the path is speed dependent.
It is thus desirable to provide robot arms with coordinated joint control that results in tool tip motion directly following a mathematical curve that accurately defines the curved path without the discontinuity effects of the prior art. In other words, it is desirable that mathematical curve fitting techniques be adapted for robot path control. The present invention is directed to this end and its implementation is facilitated by the completely digital robot control disclosed in the incorporated by reference patent applications.